Just finish debuff for E3
I heard sound of quest finish when i back to port from sortie...
and the E3 boss look like this:
» Click to show Spoiler - click again to hide... «
In E2:
-perfect S for node K (i don't think this is require

since i do not go other air node, such as L)
-defend from air raid perfect for two sortie (1 sortie have 2 air raid, both i got perfect white text)
In E3:
-do not change difficulty once i select (i choose hard

)
-get S rank for node D, H, J and A, C, K
the fleet i use to BDEHJ:
» Click to show Spoiler - click again to hide... «
and for ACIK: (i dunno how to go G from C, so i go ACEIK)
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the sequence that i do:
1 - (E2)get perfect S for node K
2 - (E2)defend from air raid perfect x2 in 1 sortie
3 - finish E2
4 - (E3) go BDEHJ
5 - (E3) go ACIK
6 - no quest complete sound after i finish ACIK, so i check and found that i only do E2 defend from air raid perfect for 1 sortie only, i try go E2, and do one more perfect defend from air raid
7 - quest finish sound once i back to my port
i don't think sequence is important, and i do E2 normal...
should be ok if do all requirements for E2 (and finish E2), then only do E3...